U.S. Pat. No. 6,830,002 (Walker) discloses a lift for watercraft that has a raised and lowered positions and is adapted to be mounted in a body of water. The lift has a substantially rectangular base with first and second pairs of vertical corner posts that are connected to and carry longitudinal beams. The base further has two transverse beams connected to the longitudinal beams. A pivoting cradle is attached to the base. Watercraft support bunks are connected to the cradle. A pair of actuators are connected on one end to the pivoting cradle and on the other end to one of the first pair of corner posts. The first pair of corner posts are adapted to be long enough that at least a portion of the corner posts are above water level of a body of water in which the lift is mounted, and the actuators are connected to the first pair of corner posts in the portion of the corner posts above the water level.
U.S. Pat. No. 5,908,264 (Hey) discloses a watercraft lift having raised and lowered positions. The lift includes a substantially rectangular base with longitudinal side beams and front, rear, and intermediate transverse beams, connected to the longitudinal beams. The intermediate transverse beam is located between the front and rear transverse beams and at a height lower than the front and rear transverse beams. Forward booms are pivotably connected to the base at a location near the front transverse beam. Rear booms are pivotably connected to the base at a location near the intermediate transverse beam. A watercraft support platform is pivotally connected to the forward and rear booms. The raising and lowering of the lift of the present invention is accomplished by an actuation assembly. In a preferred embodiments, the actuation assembly includes two dual directional high pressure hydraulic cylinders pivotally connected between the intermediate transverse beam and the rear boom. During use, the actuator assembly rotates the booms upward and forward about their pivotable connection to the base further raising the watercraft support platform and the watercraft to an overcenter position.
U.S. Pat. No. 5,184,914 (Basta) discloses upwardly extending pivoting booms are supported on a rectangular base which is submerged in water. Watercraft supports on mounting arms are connected to the pivoting booms. A double-acting hydraulic cylinder attached between the rectangular base and pivoting booms swings the pivoting booms upwardly until they are braced by boom supports on the rectangular base at an angle over center. This raising of the pivoting booms lifts the mounting arms and watercraft supports to remove a craft from the water and disposes the booms, mounting arms, and craft in a stable, secure over center configuration. Actuation of the double-acting hydraulic cylinder in the opposite direction forces the booms back out of the over center position and lowers the craft into the water.
U.S. Pat. No. 5,890,835 (Basta et al.) discloses a hydraulic lift for raising a boat out of water into a raised storage position is proposed. Pivoting booms are connected to a frame that is supportable by a bed of a body of water. A boat rack is provided at an upper portion of the pivoting booms. A hydraulic cylinder is connected between the frame and a lower portion of the pivoting booms. The pivoting booms are selectively adjustable between a lowered position wherein the rack is submerged in the water and a raised storage position wherein the rack is raised above the water. The position of the pivoting booms is controlled by a ram of the hydraulic cylinder. Importantly, the pivoting booms are maintained in the raised storage position when the ram is in a retracted position which protects the ram from corrosion and fouling. In the preferred embodiment, the pivoting booms are rotated over center when they are in the raised storage position.
U.S. Pat. No. 6,830,410 (Davidson et al.) discloses an apparatus for supporting the hull of a watercraft using a flexible bunk beam and a convex cushion attached to the beam using locking elements. The beam has a longitudinal recess with a narrow upper neck portion and a larger lower anchor portion, and the cushion has an elongated cushion locking member lockably insertable into the recess. The cushion locking member has a narrow upper neck portion and a larger lower portion sized to snuggly fit within the recess. The cushion includes internal voids and walls. The beam includes sidewalls with bores forming bearing surfaces.